By Ashlyn Seeley Everett, M.D., radiation oncologist at Alliance Cancer Care
If you or a loved one are diagnosed with cancer, you start to learn a new language. It can be very confusing and overwhelming. One of the most commonly asked questions involves scans, or imaging studies. What type of scan am I getting? What is the difference between this and the scan I had last week?
Doctors try to gather all the information necessary to make the best treatment plan for patients. Many times, this will involve some sort of biopsy, or sampling of tissue, and some sort of imaging, or scan of the body. When doctors order scans, they have to specify the type of scan and the body site to be scanned. This is specific to every individual case, and each type of imaging has advantages and disadvantages.
Types of Diagnostic Scans:
- X-rays. X-rays are a very fast, basic scan of a part of the body. They are often done to look at bones or lungs. X-rays are 2-dimensional images.
- CT, or Cat scans. CT scans are X-rays sent through a portion of the body to produce a 3-dimensional image. Doctors often use contrast, or a substance to highlight the CT scan for better visualization. CT scans are ordered for a certain part of the body, and helpful to look to see if cancer has spread to other parts of the body.
- PET-CT or PET scans. PET-CT scans combine two scans: a CT scan, as described above, and a special type of scan called a PET. For a PET scan, patients are injected with a special type of dye, often linked to a sugar molecule. The dye then travels preferentially to parts of the body that use sugar for energy, like the brain, heart, and liver. The dye also will travel to any areas of cancer, and highlight them on the scan. PET-CT is a helpful tool to determine if an area is suspicious for cancer, and can guide management if cancer has spread in the body. PET-CT scans are not useful for looking for tumors inside the brain.
- MRI or MRI scans. MRI uses magnets to produce images, not X-rays. MRI scans produce excellent soft-tissue pictures and help look at the brain, liver, breast, or muscles. MRI scans are only of a certain area of the body. MRI scans are typically longer scans, and the machinery is very loud. Be sure to alert your doctor if you have any metal in your body, like a pacemaker or defibrillator, before your MRI scan.
Your doctor will discuss the results of the scans with you. Sometimes, this can lead to additional questions rather than answers. Ultimately, your doctor wants to design the best treatment plan and will discuss why additional tests may be recommended.
If radiation is part of your cancer treatment, you will have other types of scans to guide your radiation treatments. This has allowed radiation treatment to become more accurate and precise.
- CT-simulation. You can read more about simulation here. This is a CT scan that is used to target radiation customized for your body and tumor. You do not get a report from this type of CT scan.
- X-rays. Often, x-rays are done before radiation treatment to verify that your body is in the correct position for treatment by looking at the bones. This is to ensure your treatment is accurate.
- CT-during treatments. At Alliance Cancer Care, we have the capability of using CT scans during radiation treatment to provide IGRT, or image-guided radiation therapy. This can ensure that your body is in the correct position, and that radiation is going to the target area.
Imaging is a very important part of cancer treatment and is particularly important with radiation treatments. After your treatment, doctors will often order scans to ensure there is no sign of cancer regrowth or spread. Your doctor will recommend the type and the frequency of scans for your particular situation.
Some scans are useful in screening for cancer, too. Mammograms are X-rays of the breast to look for early-stage breast cancer. In patients older than 50 with a long smoking history, a low dose CT scan of the lungs can be used to find early-stage lung cancers.
Ask your doctor if you are a candidate for screening with a mammogram or a low-dose CT of the lung.